How does your company handle test failures?

For many years, most of the projects I worked on were systems that had never been built before in any shape or form. As a consequence, many of the iterations for each of these projects included significant and sometimes spectacular failures as we moved closer to a system that could perform its tasks successfully in an increasingly wider circle of environmental conditions. These path-finding designs needed to be able to operate in a hostile environment (low earth orbit), and they needed to be able to make autonomous decisions on their own as there was no way to guarantee that instructions could come from a central location in a timely fashion.

The complete units themselves were unique prototypes with no more than two iterations in existence at a time. It would take several months to build each unit and develop the procedures by which we would stress and test what the unit could do. The testing process took many more months as the system integration team moved through ground-based testing and eventually moved on to space-based testing. A necessary cost of deploying the units would be to lose it when it reentered the Earth’s atmosphere, but a primary goal for each stage of testing was to collect as much data as possible from the unit until it was no longer able to operate and/or transmit telemetry about its internal state of health.

During each stage of testing, the unit was placed into an environment that would minimize the amount of damage the unit would physically be subjected to (such as operating the unit within a netted room that would prevent the unit from crashing into the floor, walls, or ceiling). The preparation work for each formal test consisted of weeks of refining all of the details in a written test procedure that fortyish people would follow exactly. Any deviations as the final test run would flag a possible abort of the test run.

Despite all of these precautions, sometimes things just did not behave the way the team expected. In each failure case, it was essential that the post mortem team be able to explicitly identify what went wrong and why so that future iterations of the unit would not repeat those failures. Because we were learning how to build a completely autonomous system that had to properly react to a range of uncertain environmental conditions, it could sometimes take a significant effort to identify root causes for failures.

Surprisingly, it also took a lot of effort to prove that the system did not experience any failures that we were not able to identify by simple observation during operation. It took a team of people analyzing the telemetry data days to determine whether the interactions between the various subsystems were behaving correctly or had coincidently behaved in an expected fashion during the test run.

The company knew we were going to experience many failures during this process, but the pressure was always present to produce a system that worked flawlessly. However, when the difference between a flawless operation and one that experienced a subtle, but potentially catastrophic anomaly rests on nuanced interpretation of the telemetry data, it is essential that the development team is not afraid to identify possible anomalies and follow them up with robust analysis.

In this project, a series of failures was the norm, but for how many projects is a sequence of system failures acceptable? Do you feel comfortable raising a flag for potential problems in a design or test run? Does how your company handles failure affect what threshold you apply to searching for anomalies and teasing out true root causes? Or is it safer to search a little less diligently and let said anomalies slip through and be discovered later when you might not be on the project anymore? How does your company handle failures?